The present invention relates to a class of polyetherimide blends comprising a specified polyetherimide and a polyester that have certain improved physical properties.
Certain blends of polyetherimides and other polymers are known. For example, U.S. Pat. No. 4,259,458 discloses a blend containing a polyarylate, a polyester, and at least one thermoplastic polymer selected from the group consisting of an aromatic polycarbonate, a styrene resin, an alkyl acrylate resin, a polyurethane, a vinyl chloride polymer, a poly(aryl ether), a copolyetherester block polymer or a polyhydroxyether. High molecular weight polyesters and particularly linear polyesters derived from 1,4-cyclohexane-dimethanol have been available for a number of years. These are described inter alia in Kilber et al, U.S. Pat. No. 2,901,466. This patent discloses that such polyesters are particularly advantageous as film and fiber-formers.
It has now been unexpectedly discovered that blends of a specified polyetherimide resin and a poly(cyclohexane-dimethylene arylate) exhibit an improvement in impact strength and other improved physical properties over the unmodified polyetherimide resins. The compositions disclosed herein have utility in injection molding, extrusion and other plastic forming operations.